Tissues at Issue

By Walt Hearn

Serratia marcescens bacteria

It's not always clear whether the biblical words “flesh” and “blood” are meant to be taken literally or figuratively. In Exodus 16:3, the phrase, “the fleshpots of Egypt,” seems to refer to the cooking of meat. It makes more sense for Israelite refugees to be nostalgic about that aroma than about “sins of the flesh.” Of course the Bible has a lot to say about those, too.

Flesh is at times contrasted with “spirit” in the Bible, as in Jesus' oft-quoted words to his closest friends who fell asleep during their watch: “The spirit indeed is willing, but the flesh is weak” (Mark 14:38). In many figurative uses, flesh seems to refer to less manageable, base, or unsavory aspects of human life. Yet, as spirit, Jesus “became flesh and lived among us” (John 1:14), demonstrating his full (but still godly) humanity on earth and showing us how to be more fully human (and godly) ourselves.

Controversy lives on in the Christian community over how to understand a few words Jesus uttered at the end of his final Passover meal. All three synoptic Gospels record that Jesus handed pieces of bread to the disciples who ate with him, referring to the bread as “my body.” The wine he poured for them, he called “my blood.” Christians agree that Jesus was thus announcing his imminent sacrifice for the sins of the world, but disagree on whether he meant to initiate a kind of solemn ritual. The most literal interpretation of “This is my body, broken for you” is used to justify the Roman Catholic performance of such a rite. As I understand it, a miraculous transformation of the physical bread and wine into the real presence of Christ is at the heart of the Eucharistic doctrine called “transubstantiation.” Shying away from that doctrine, Eastern Orthodox and Protestant churches (including other sacramental ones) have developed other interpretations to maintain the spiritual power of Holy Communion.

At the low-church end of the spectrum, where “the priesthood of all believers” is emphasized, a fully metaphorical interpretation is accepted. Southern Baptists in the U.S., for example, do not regard “the Lord's supper” as a sacrament at all. They generally call it an “ordinance” and think of it as a symbolic act of obedience to remind believers of Christ's crucifixion. Personally, I'm probably as low-church as anyone can get (some might even say “sub-church”). That is, I'm not sure that Jesus was saying more to his followers than “Whenever you sit down to eat, remember that I died for you.”

[Tangential Tale # 1: Not everyone knows that “hocus-pocus” is a corrupt version of the Latin Hoc est corpus meum, said by priests over the Sacrament. I know, because as a youth, my older brother Dale was a semi-professional magician with the stage name “Elad.” Assisting him at kids' birthday parties, I was “Retlaw.” I learned about hocus-pocus from reading my brother's Johnson Smith catalogs and The Linking Ring, journal of the International Brotherhood of Magicians.]

Blood Chemistry

In common parlance, blood remains metaphorically equivalent to “life.” In the Mosaic Law, the blood of choice livestock was sprinkled on an altar to atone for sin but was never to be eaten (Leviticus 17). Wild game that died without being bled-out was off the menu, too. Centuries later, the first Jews to become Christians thought that no one who ignored such dietary laws could properly worship their resurrected Messiah. When gentiles also began to follow Jesus, to avoid giving offense to the earliest believers they were instructed, among other things, not to eat blood (Acts 21:25). Paul, apostle to the gentiles, argued that Christian were free to eat anything (except food that might have been offered to pagan idols) but should not flaunt their freedom before “weaker brothers” (see Romans 14 and 1 Corinthians 8). Christians still differ on some food issues. All the Seventh Day Adventists I've known have tended to be vegetarians, some perhaps to promote the ethical treatment of animals or for health reasons.

[Tangential Tale # 2: Early in my scientific career, I learned that the Jewish kosher slaughtering of animals still goes on. (The equivalent Islamic procedure is called halal.) I went with a physiologist colleague to a Houston slaughterhouse to obtain hypothalamic tissue from fresh beef brains. We watched steers prodded through a chute, one at a time, to be shot in the back of the head by a guy sitting on top of the chute with a .22 rifle. Even with such a small bullet, that cowboy seldom failed to smash the grape-sized hypothalamus. We were told to return on a Friday, when an orthodox rabbi would be there. We watched him slit live animals' throats so they died from loss of blood, pumped out by a still-beating heart. Only a few animals were killed that way, so my friend could barely dissect enough tissue to be usable. After I left Baylor Med, he switched to sheep brains. Although the part of the brain he was after was smaller in sheep, he managed to collect thousands of them for his research.]

Today, in the vocabulary of science, literal flesh has been supplanted by “soft tissue” but literal blood plays an important role. In my own biochemical research I had little to do with blood or any other animal tissue. I did study a bacterial pigment bearing a certain resemblance to heme, active site of the blood protein hemoglobin. That project began when another friend at Baylor Med, microbiologist Robert P. Williams, introduced me to Serratia marcescens, a gram-negative bacterium once known as Baccilus prodigiosus. Its cultures had the property of looking much like the colorless, better known E. coli, when grown at body temperature (37o C), but being bright red when grown for days at room temperature (25o C).

At the time, the chemical structure of the blood pigment heme was known, but that of the bacterial pigment prodigiosin was still in dispute. Prodigiosin was composed of ring-shaped subunits, but had only three of them. Heme had four, arranged in a larger ring around a single atom of iron. (Blood can deliver oxygen to animal tissues because that special iron-atom binds oxygen reversibly. That truly life-giving property had made heme of great interest.) By the time I came along, other biochemists were busily working out details of heme's biosynthetic pathway. I hoped to do the same for prodigiosin, using Serratia mutants Bob had produced by irradiating cultures with UV light. My first grant applications claimed that my prodigiosin research might shed light on how heme was assembled in animals. After I'd helped nail down prodigiosin's correct structure, I changed my tune: I then argued that studying its biosynthesis was still important--but because it would be utterlydifferent from that of heme.

Before the 1950s, S. marcescens was not considered a human pathogen. Because it was safe, and its red cultures were easy to spot, early in the Cold War the U.S. military used it to test the feasibility of germ warfare by releasing clouds of it over San Francisco. The feds kept the tests secret for twenty years, then acknowledged that after the tests, S. marcescens had shown up in the blood of some S.F. hospital patients who died with septicemia (now called sepsis). One of my students read about that and opted out of my research group, even though we had grown the bug safely for years. Genomic research is now showing that our bodies are cohabited by perhaps thousands of species of microorganisms. Back then I tried to explain that septicemia might easily develop in very sick patients with compromised immune systems, but the growth of a particular bug in such a patient didn't mean that it had caused that person's death. For that student, it was too late. The psychological damage had already been done.

Historically, Serratia marcescens probably did another kind of damage related to this discussion. Its tendency to grow on warm, moist bread provided a plausible scientific explanation for at least some of the “bleeding host” miracles occurring at Catholic masses during the Middle Ages. I've been told that a painting by Raphael of a famous 13th-century miracle of that type hangs in the Vatican. The bacillus was first identified in 1819 in Padua, Italy, as a spontaneous red growth on a batch of polenta. The discoverer, a pharmacist from Venice named Bartolomeo Bizio, suggested that such red spots could in past times have been assumed to be miraculous appearances of blood.

[Tangential Tale # 3: While working on prodiogosin, I ran across some ancient accounts by Greek and Roman historians whose names I've forgotten. One account gave me the impression that S. marcescens may have been around in antiquity. It told of the siege of the island city of Tyre (then part of Phoenicia, now of Lebanon) in 332 BC, by an army of Alexander the Great on its way to do battle with Persia (now Iran). Evidently, when traveling with his army, Alexander took along soothsayers from his native Macedonia to advise him. Frustrated over his failure to take Tyre, he ordered them to say him some sooth. Some of his soldiers had found “drops of blood” inside their bread ration, so he asked his advisers what to make of it. They prophesied that the blood predicted the island's defeat. Alexander roused his men and led them on one more attack, which was successful. That story reminded me of the saying journalists have about what gets on the front page of a newspaper: “If it bleeds, it leads.”]

Blood Kinship

In the context of today's headlines, blood also stands for the continuity or connectedness of life. The biblical idea that God made us all of “one flesh” or “one blood” still counts. We regard family members as “our own flesh and blood,” and even speak of the “blood lines” of thoroughbred race horses. With our new ability to sort out individual differences in human genomes, we can attain a higher level of certainty in constructing “family trees.” Back in 1901, Austrian physician Karl Landsteiner published his discovery of the relatively simple ABO blood-typing system. His grasp of inherited antigens on red blood cells put immunology and serology on a firm scientific basis. Today it still prevents many deaths from blood transfusions or organ transplants. After winning the 1930 Nobel Prize in physiology or medicine, Landsteiner went on to discover other important blood groupings, including the Rh factor.

The idea that we're more closely connected “by blood” to some people than to others has great social consequences. We tend to trust people to whom we are socially bonded, with our highest level of trust likely to be within our immediate family. Trust begins to attenuate as we move outward to our extended family, then to clan, tribe, nation, race, or religion. Westerners may think of ourselves primarily as individuals but, elsewhere in the world, blood ties really matter. In the Middle East, clan and tribe seem to be as relevant today as they were in Old Testament times. I once thought about writing my memoirs, then realized that I knew almost nothing about my biological ancestry. Yet I can trace my scholarly ancestry back to 18th-century French chemist Antoine Lavoisier. My PhD mentor, Herb Carter, studied under Carl Marvel, he under Alfred Noyes, and so on. My “scientific blood line” includes 19th-century German chemists Friedrich Wőhler and Leopold Gmelin. Instead of genes, from those ancestors I may have inherited certain “memes” about the value of scientific research, or even about how to do it. It seems natural for me to “think like a chemist.”

The more we cherish our closest “blood groups,” the more “other” everyone else seems to become. People who cling too tightly to convictions or doctrines may get defensive about them and even feel a need to attack people who differ. Does it have to be that way? It's hard for Christians to believe that Sunni and Shia Muslims in the Middle East are (literally) at each others' throats over something that happened in the 7th century. Yet to me, the rhetoric of Christian fundamentalists at times sounds as harsh as that of Islamic fundamentalists. For example, some “Christian Reconstructionists” have written that modern Christians should strictly obey the Old Testament by (literally) stoning to death homosexuals and disobedient children. Evidently, since 1945, some Jehovah's Witnesses would rather see their own children die during surgery than permit them to have a blood transfusion, arguing that only God can give life, and “the life is in the blood.” That's how “we evangelicals” appear to others.

Do Muslims pick and choose? I'm afraid so. Do Christians pick and choose? So it seems. Do scientists? Probably, if to a lesser extent. Political polarization threatens to tear the world apart. Can we do anything to repair that? Well, it might help if all God's people would lighten up a bit, think more openly, and learn to live with ambiguity. As a Brit might say, we should bloody well give it a go.

Walter R. Hearn grew up in Houston and majored in chemistry at Rice University. He received a Ph.D. in biochemistry at the University of Illinois in 1951. After doing research for a year at Yale Medical School and for three years at Baylor College of Medicine, he spent 17 years on the biochemistry faculty at Iowa State University. His research interests included peptide chemistry, hypothalamic hormones, and bacterial pigment biosynthesis.

For five years he was a Visiting Biologist to Colleges for the American Institute of Biological Sciences. He is a Fellow and Life Member of AAAS and an Emeritus member of the American Chemical Society. In 1972 he switched professions and moved to Berkeley to do free-lance editorial work with his wife Virginia. They have edited periodicals and some 200 books, largely for Christian publishers. Walt joined ASA while he was in grad school and served on the Council in the 1960s. From 1969 to 1993 he edited the ASA newsletter. He was a coauthor of the widely distributed publication, Teaching Science in a Climate of Controversy (ASA, 1986) and author of Being a Christian in Science (IVP, 1997).

He has also contributed chapters to a number of books, the latest being "Creation Matters" in Darwin and the Bible: The Cultural Confrontation (Penguin Academic, 2009), edited by anthropologists Richard Robbins and Mark Cohen. His articles, reviews, and poems have appeared in such publications as Perspectives on Science & Christian Faith and the Berkeley publication Radix, for which Ginny has been copy editor for over 40 years. Walt was once "poetry rejection editor" for Radix magazine. Walt and Ginny have strong IVCF backgrounds, helped to launch New College for Advanced Christian Studies in the 1980s, and are members of Berkeley's First Presbyterian Church.